cros_workon: print out short summary of what has been done for start/stop
cros_workon: print out short summary of what has been done for start/stop

BUG=6325
TEST=cros_workon start and stop for board and host and see it work

Change-Id: Ic0680a273391fdf93b6ebbe0e34497807f31f240

Review URL: http://codereview.chromium.org/3352002

endocode/scripts,gtank/scripts,nicescale/scripts,BugRoger/scripts,sigma/coreos-scripts,sigma/coreos-scripts,bcwaldon/coreos-scripts,bcwaldon/coreos-scripts,vmware/coreos-scripts,crawford/scripts,smilart/scripts,endocode/scripts,mischief/scripts,mischief/scripts,smilart/scripts,mjg59/scripts,mjg59/scripts,vmware/coreos-scripts,nicescale/scripts,gtank/scripts,andrejro/coreos--scripts,BugRoger/scripts,andrejro/coreos--scripts,marineam/coreos-scripts,coreos/scripts,zhang0137/scripts,fivethreeo/scripts,mischief/scripts,smilart/scripts,andrejro/coreos--scripts,mjg59/scripts,vmware/coreos-scripts,trnubo/scripts,trnubo/scripts,coreos/scripts,zhang0137/scripts,glevand/coreos--scripts,nicescale/scripts,glevand/coreos--scripts,fivethreeo/scripts,BugRoger/scripts,fivethreeo/scripts,bcwaldon/coreos-scripts,zhang0137/scripts,sigma/coreos-scripts,marineam/coreos-scripts,marineam/coreos-scripts,crawford/scripts,trnubo/scripts,endocode/scripts,gtank/scripts,crawford/scripts